1. Field of the Invention
The present invention relates to a book binding apparatus having a stacker, and more particularly, it relates to a book binding apparatus in which imaged sheets are bound as a book and which is applicable to an on-line system wherein a plurality of image forming apparatuses required for forming images on sheets successively, a book binding apparatus for bookbinding the sheets on which the images were formed and a sorting and containing apparatus for sorting and containing the bookbound sheet bundles are interconnected, and also relates to an image forming apparatus having such a book binding apparatus.
2. Related Background Art
In the past, when a plurality of sheets on which images were formed are automatically glue-bound to obtain a book, an on-line system wherein a plurality of apparatuses required for performing such jobs are interconnected has been used.
For example, the on-line system includes (1) a reading and sheet supplying apparatus comprising an original setting portion for setting an original, an optical system for scanning the original, and a sheet supplying apparatus for containing a number of sheets and for supplying the sheet, (2) an image forming apparatus for forming an image on the sheet supplied from the sheet supplying apparatus, (3) a book binding apparatus for bookbinding the sheets on which the images were formed, and (4) a sheet sorting and containing apparatus for sorting and containing the bookbound or finished sheet bundles or the sheets. These apparatuses are interconnected in series.
When the sheet bundle is bookbound in the book binding apparatus, the sheet bundle aligned in a sheet align tray is glue-bound by a gluing binder. A bind tape used with the gluing binder comprises a tape-shaped sheet on which paste or glue of a hot melt type is coated. The bind tape is abutted against the sheet bundle and is adhered to the sheet bundle by melting the glue by a heater.
In the conventional book binding apparatus of the on-line system including the image forming apparatus, a sheet entrance portion, a sheet bundle aligning means, a convey means and a stacker are arranged in series, and the convey means is of handling type. According to this handling type, in bookbinding the sheet bundle, the sheets successively fed from the sheet entrance portion are aligned in the aligning means as a sheet bundle, and then the bind tape is abutted against the sheet bundle and is heated by the heater to bookbind the sheet bundle, and the bookbound sheet bundle is contained in the stacker. When a predetermined number of sheet bundles are bookbound or when the stacker is filled with the sheet bundles, the stacker is unloaded to retract a tray of the stacker out of the apparatus so that an operator can remove the sheet bundles from the tray. After the operator removes the sheet bundles, the tray is automatically returned into the apparatus, thereby achieving a stand-by condition. In this case, the bookbinding operation of the book binding apparatus will be stopped during the time from the unloaded condition to the stand-by condition, thereby reducing the productivity.
Further, an easy book binding device such as a stapler or folder as a finishing apparatus arranged upstream of the book binding apparatus must be also stopped, thus reducing the working ratio.
On the other hand, since the sheets on which the images were formed are stacked in a stacker or a discharge tray, the operator must sort such sheets manually. In order to minimize the sorting labor, recently, the improvement in a sorting apparatus such as a sorter, a mail box and a multi client sorter have been requested.
However, in the book binding apparatus having the above-mentioned modules interconnected in series, since the convey means is operated synchronously with the bookbinding operation, the productivity is changed in accordance with the bookbinding time. The reduction of the productivity of the entire system due to presence of the book binding apparatus which requires the longest tact time is not preferable for the high speed image forming apparatus included in the system from the view point of cost and productive capacity.
Further, in the on-line system, when the image forming apparatus and the finisher are arranged upstream of the book binding apparatus and the sorting apparatus is arranged downstream of the book binding apparatus, the single sheet, a stapled sheet bundle or a folded sheet bundle (which is not bound by the bind tape and which is obtained by the finisher) must be sent to the sorting apparatus through a convey portion of the book binding apparatus. In the above-mentioned conventional book binding apparatus having the modules interconnected in series, since the last process is effected in the stacker, the bookbound sheet bundle obtained in the book binding apparatus and other sheet bundle(s) obtained in the finisher must be contained in the same stacker in mixture or the jobs must be performed independently. Thus, in the above-mentioned conventional on-line system, the sorting apparatus cannot be arranged at the downstream side of the book binding apparatus.